Membership Plugin causing redirect loop

We have the membership plugin installed on one of our sites to restrict access to Marketpress. When membership is activated, however, it is causing this error (message from Chrome browser, but IE is having trouble also):

This webpage has a redirect loop
The webpage at http://www.hcgmax.com/hcg-max-professionals has resulted in too many redirects. Clearing your cookies for this site or allowing third-party cookies may fix the problem. If not, it is possibly a server configuration issue and not a problem with your computer.

Any ideas how to correct the issue? I can pm admin login if need be.